Etching systems, such as ion beam etching systems, are employed in various industries for fabricating devices on wafers. The industries may include, for example, magnetic read/write and storage, optical system, semiconductor, and micro-electromechanical system (MEMS) industries.
An ion beam etching system typically includes a grid assembly disposed between an ion source unit and a wafer for providing a broad ion beam to etch the wafer. The ion beam may etch away unprotected/unwanted material from the wafer for forming particular device structures. A substantial amount of the unwanted material that is etched away from the wafer as well as the surrounding chamber wall areas exposed to the broad ion beam may sputter and adhere to the grid assembly. The deposition of the unwanted material on the grid assembly may introduce mechanical stress on the grid assembly, thereby causing the grid assembly to warp. The warping of the grid assembly may degrade the uniformity of the ion beam. As a result, the yield of device fabrication may be substantially reduced.
To maintain an acceptable yield, grid assemblies may need to be frequently replaced. However, the frequent replacement of the grid assemblies may undesirably incur material costs, labor costs, system down time, and waste of resource.
In etching larger wafers, ion beam uniformity across each wafer may be especially crucial for achieving a desirable fabrication yield. At the same time, more unwanted material may be etched away from wafers and sputtered on the grid assembly to cause warping of the grid assembly. As a result, the frequency of grid assembly replacement may need to be increased, and additional manufacturing costs may be incurred.